chore(deps): update cachix/install-nix-action action to v31 (#77)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -10,5 +10,5 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4
-    - uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30
+    - uses: cachix/install-nix-action@91a071959513ca103b54280ac0bef5b825791d4d # v31
     - run: ./ci.sh